On Left 4 dead 2 I downloaded a map in www.l4dmaps.com, and the map is called "Nacht der Untoten, when I downloaded it, I extracted the files using Winrar into "C:\Program Files (x86)\Steam\SteamApps\common\Left 4 Dead 2\left4dead2\addons" and the file was called "nazi_zombies_ndu" but when I went to my Left 4 dead 2.exe, I went to Add-Ons the map was there, but when I went to Campaign and Single player it said "None of the installed Addons support Campaign mode", then I went to watch youtube vids of the reason where is Add-On support, the videos didn't say "None of the installed Addons support Campaign mode"! and the map worked perfectly for them! and I found out that Valve deleted the tool "Left 4 Dead Add-On support!

How can I download custom maps?! and how can I get Add-On support?! Plz help!!!